I think you want to tip those now (assuming you have not trained a tip-bearing apple). You need to encourage spur formation and minimize growth coming out in all directions.

I suggest leaving the more vertical shoots on the top branches for now and remove them from the lower branches. Why is because those top tiers will try to grow faster and shade out the lower branches and they'll never keep up if you go all horizontal everywhere. After the lower branches get some growth you can then start letting top go to "keep up" with the lower and prune the vertical growth out. This isn't from tried and true, this is from tried and failure. Give me a few years to see if it's tried and true but judging from the old ones (not really failures) vs the new the top will always want to outgrow the bottom and if it's allowed to start out like that the bottom kind of gives up. Next year don't wait for some of that. Anything coming off the main trunk should be rubbed out as soon as you see it and it's just a bud. Those really long ones can be nipped when you think they're getting long enough for your tastes, just pinch the end off.

Melissa, all apple trees from nurseries today are grafted to a root stock. It is the root stock that determines the size of the tree. An espalier tree is just the way the tree is trained to grow and not a type of tree. In your 4' x 25' area, with the right root stock, you could get as many as 6 apple trees planted 4' apart. We have semi-dwarf trees planted 4' apart in our tree rows (we have 17,000 trees in our orchard). In our retail nursery, we stock all dwarf and semi-dwarf trees and tell our customers what root stock they are getting. Most nurseries do not do that so you have no idea what size tree you might end up with. The most common dwarf root stock is Bud 9 or B9 and semi-dwarf is M26 or M9. If you contact Whiffletree Farm & Nursery, they can help you with the right trees for your situation. I know they grow a super-dwarf tree on M27 root stock that gets no taller than 6'-7'. Whiffletree is north of Kitchener-Waterloo, Ontario. Her is one of our tree rows planted to espalier on M26 root stock spaced 3' apart. We also have a 3,000 tree apple tree maze planted to espalier! Hope this helps!

I did what you are describing with lower branches. If they are going in the right section why wouldn't you use them. Seems to have worked fine so far several years down the road.